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Falcon Heavy - General Discussion

Discussion in 'SpaceX' started by JRod0802, Apr 5, 2011.

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  1. Cosmacelf

    Cosmacelf Well-Known Member

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    If the story about Gwynne Shotwell running down the corridor to stop Elon cancelling Falcon Heavy is correct, she should get a raise ;)
     
  2. doug

    doug Administrator / Head Moderator

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    Where does one read that story?
     
  3. Cosmacelf

    Cosmacelf Well-Known Member

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    I don't remember exactly. I've read four books about Elon and SpaceX, so I would guess it was in one of those. Basically something like 2 years before Falcon Heavy launched (so three years ago), Elon and the engineers were getting frustrated with some hard technical problems and in a fit of pique, Elon threw his hands up and said he was going to cancel the rocket. The fact that BFR was in the works at the time probably had something to do with his thinking as well. Anyways, Gwynne heard about this shortly thereafter and apparently went running down the corridors in her high heels to intercept Elon and remind him that they had already sold a falcon heavy launch to the Air Force and there was NO WAY they could back out if they wanted to keep SpaceX afloat. At the time, the military was still very much doubting SpaceX was a real company.
     
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  4. ecarfan

    ecarfan Well-Known Member

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    I’ve read the first three books you listed and do not recall that story about Gwynne saving FH from cancellation. But that doesn’t mean it’s not in there somewhere. ;)

    Do you think the fourth book in your list is worth buying?
     
  5. Cosmacelf

    Cosmacelf Well-Known Member

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    It's by far the weakest of the four books, so probably not. Hmmm, looks like I'll have to chase down a source for that story, if only to prove that I'm not losing my mind.
     
  6. Cosmacelf

    Cosmacelf Well-Known Member

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    OK, here's A reference to the story (which also is an interesting read in itself):

    Bloomberg - Are you a robot?

    I'm pretty sure that Bloomberg article got this tale from somewhere else...
     
  7. Cosmacelf

    Cosmacelf Well-Known Member

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    OK I am now officially freaked out about Google. After I posted #623 in this thread an hour ago, I thought I should do a google search to try to find a reference to Shotwell saving the Falcon Heavy. Well, the top post on page 2 of a google search for "did gwynne shotwell save the falcon heavy from cancellation" was ... my post #623.

    How the &^%^& did Google index a random forum post (out of millions new pages created every hour) in ONE HOUR?
     
  8. mspohr

    mspohr Well-Known Member

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    It's scary how much Google knows. Much more than most people think.
     
  9. ecarfan

    ecarfan Well-Known Member

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    Circular references are the bane of the internet. Google “proved” your Gwynne story by referencing...yourself! ;)

    Google crawls long established, highly dynamic, content rich sites like TMC constantly and has done so for years. It’s normal.
     
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  10. Oil4AsphaultOnly

    Oil4AsphaultOnly Supporting Member

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    It was in one of Shotwell's college presentations or interviews, when someone asked her about some of the challenges she's faced working for Elon. I remember that same story, but I don't recall it ever being quoted in a book.
     
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  11. e-FTW

    e-FTW New electron smell

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    It’s on the Internet, so it is true! Looks Google ranks it that high!
    Heh
     
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  12. Oil4AsphaultOnly

    Oil4AsphaultOnly Supporting Member

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  13. Oil4AsphaultOnly

    Oil4AsphaultOnly Supporting Member

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    Okay, this is now royally bugging me. It was NOT in the madrid interview!

    Aside from the Bloomberg article, the only clue I could find about Musk cancelling Falcon Heavy was him directly saying it during the post launch interview (14:58 mark):

    The closest I got to Gwynne commenting about working for Elon came from her TED talk: Transcript of "SpaceX's plan to fly you across the globe in 30 minutes"

    I'm beginning to think you might be right.
     
  14. bxr140

    bxr140 Active Member

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    So...its a little more complicated than that. Those last few years aren't really a huge revenue benefit to a program, especially when compared to what the additional capital could have done to improve the performance of the payload...which of course would benefit revenue on on day 1 instead of year 16. I've used this analogy before, but its kind like Tesla saying "your 100D is gonna last 500,000 miles, but if you pay us an extra $15k right now we'll make sure it lasts 600,000". I don't know anyone that would take that deal over putting that $15k toward upgrading to a P100D. Anyway, basically every GEOcomm is contracted at 15 years. That's the right number for a bunch of different reasons; that's the number everyone uses, operators and manufacturers alike. Even if you add propulsion to last longer than 15 years (propulsion is the practical mission life driver), the components aren't designed to last longer than 15 years, so you really start to run into sub optimal operations modes where you're running on less power because you've lost strings on the array, you're running on redundant electronics, etc. That's not to say satellites last just 15 years, that's not to say operators don't want them to last longer...but they're almost never designed to last more than that.

    Beyond design margins typically enabling longer than contracted life, here's how you end up with more than 15 years: Basically, a particular dry mass spacecraft necessitates a particular amount of fuel to last 15 years, so that ends up the baseline fuel load. As the payload progresses through design and production, the mass budget burns down uncertainty and the satellite can come in underweight. Good stuff there. The other element is that the fuel tanks aren't really sized to the payload, there are just a few options for a given spacecraft platform. Because the obvious design choice to use the tank option that's too big for the mission as oppose to too small, you almost always end up with a planned unused amount of volume in the tank(s). So, combine that lighter than planned spacecraft with available tank volume, and at that point its almost a freebie to fill the tanks up to the contracted launch/separated mass.

    The next layer is that often launchers will hold margin that can be released as performance (or in some other way can provide higher than contracted performance)--so if the launch loads calculations permit, in the case where the launcher can accommodate a heaver than planned spacecraft you can fill up the tanks even more, some times to the point of [almost] literally 'topping them off'.

    If I were to speculate, I'd guess some combination of these things happened to give more than 15 years EOL:
    1: SpaceX went to Arabsat with a screaming deal, enough to make a legacy Geocom operator look past both the elevated risk of failure to their business model and also the increased insurance premium for launching on something with a higher statistical probability of failure.
    2. Lockheed oversold their product and ended up being mass critical for a F9 launch. What that really means is the satellite needs to expend more fuel during orbit raising and, as such, doesn't have enough fuel to last the contracted 15 years. SpaceX swoops in to save the day and enable freebie years to boot.
    3. FH performance almost certainly would have allowed Arabsat to top off the tanks.

    Note that FH does not get a spacecraft to its orbit any faster than any other launcher, unless the payload is planning to perform electric orbit raising. At that point FH would put the payload in a better (and likely far better) 'starting' orbit.

    I'm also not sure how much this launch will actually influence the FH market. It will help settle the stomachs of the underwriting community for sure, but all existing operators are currently talking to SpaceX about how to make FH work for their payloads. (News flash: Its not as easy as it might seem). From everyone's perspective, its just nice to see SpaceX is delivering the product that they're already talking about.
     
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